1. Field of the Invention
The present invention relates to an integrated circuit device for driving a flat display board or the like.
2. Description of the Related Art
A fluorescent display module is built in a dot character type fluorescent display device which is a flat display unit. FIG. 1 is a schematic diagram showing a conventional fluorescent display module. FIG. 2 is a schematic illustration showing one divided display part 110 in FIG. 1. FIG. 3 is a schematic illustration showing anode lines 102 in FIG. 1.
As shown in FIG. 1, a conventional fluorescent display module is provided with a fluorescent character display tube 100 which is a flat display board, and an integrated circuit device 300 for driving the fluorescent character display tube 100. The fluorescent character display tube 100 has a capability of displaying, for example, 15-digit alphanumeric characters and katakanas (angular Japanese phonetic syllabary). Such a fluorescent character display tube 100 includes fifteen divided display parts 110. One divided display part 110 is composed of 5(crosswise)xc3x978(lengthwise) dots of minimum light emission display. Each of 5(crosswise)xc3x978(lengthwise) anodes 101 (A1-A40) is composed of one dot of minimum light emission unit, as shown in FIG. 2.
The fluorescent character display tube 100 includes, as shown in FIG. 1, input terminals 103 (AI1-AI40), and forty anode lines 102 are connected to the input terminals AI1-AI40, respectively. The anodes 101, which are disposed at the same position at each digit, are commonly connected to respective input terminal 103 (AI1-AI40) by the anode lines 102, as shown in FIG. 3. For example, fifteen anodes A5 are connected to the input terminal AI5 by one anode line 102.
Furthermore, the fluorescent character display tube 100 includes, as shown in FIG. 1, input terminals 106 (GI1-GI15), and fifteen grid lines 105 are connected to the input terminals GI1-GI15, respectively. Each digit has one grid 104 (GI1-GI15) as a digit electrode, which is connected to the input terminals 106 (GI1-GI15), respectively.
The integrated circuit device 300 has output terminals 311 (ao1-ao40) and 312 (go1-go15). From the output terminals 311 (ao1-ao40), outputted are anode voltages that drive the anodes 101 corresponding to a display pattern. From the output terminals 312 (go1-go15), outputted is a grid voltage that drives each grid 104 by time-sharing.
The fluorescent character display tube 100 and the integrated circuit device 300 are mounted on a printed circuit board (not shown). On the printed circuit board, there are provided wirings 325 for connecting the input terminals 103 of fluorescent character display tube 100 and the output terminals 311 of integrated circuit device 300. There are provided with, on the printed circuit board, wirings 326 for connecting the input terminals 106 of fluorescent character display tube 100 and the output terminals 312 of integrated circuit device 300.
FIG. 4 is a block diagram showing the integrated circuit device 300 in FIG. 1.
The integrated circuit device 300 includes a control part 301 that inputs and outputs various signals including display data for the fluorescent character display tube 100. The integrated circuit device 300 also includes a memory part 302 that consists of RAM for writing and reading display data and the like and ROM for reading only according to output signals from the control part 301. Furthermore, the integrated circuit device 300 includes an anode drive part 303 for outputting anode voltages according to the display data read from the memory part 302 and obtained via the control part 301, and a grid drive part 304 for outputting grid voltages sequentially to each grid 104 by time sharing, based on timing signals from the control part 301.
The control part 301 has a counting part 305 for reading display data from the memory part 302 as parallel data according to a count signal, and a parallel/serial conversion part 306 for outputting parallel data converted into serial data. To the output side of anode drive part 303, connected is the output terminals 311 (ao1-ao40) for anode voltage, and to the output side of grid drive part 304, the output terminals 312 (go1-go15) for grid voltage is connected.
FIG. 5 is an illustration showing data stored in the memory part 302 in a conventional integrated circuit device 300.
As shown in FIG. 5, in the memory part 302, stored are 5(crosswise)xc3x978(lengthwise) bits of display data to be displayed at each digit of the fluorescent character display tube 100. The address of display data at each bit is designated by the row address R0-R7 and the column address C0-C4 corresponding to the anode A1-A40.
Now, operations of the conventional fluorescent display module configured as mentioned above will be described.
When a count signal from the counting part 305 is supplied for the memory part 302, the display data of the digits to be displayed are read sequentially from the memory part 302 as parallel data for each 5 bits of column addresses C0-C4, from the row addresses R0 through the row addresses R7. The read parallel data are outputted after their 5-bit data have been serialized by the parallel/serial conversion part 306, from the C0 side toward the C4 side of column address. The serial data are inputted sequentially into a shift register included in the anode drive part 303. Once all of the 5(crosswise) xc3x978(lengthwise) bits of display data have been inputted into the shift register, anode voltages for anodes A1-A40 are outputted simultaneously from the output terminals 311 (ao1-ao40). At the same time, a timing signal is supplied from the control part 301 to the grid drive part 304, and grid voltages from the output terminals 312 (go1-go15) are applied to the digits that are driven in response with the timing signal.
Successively in the same fashion, an anode voltage and a grid voltage are sequentially supplied to respective anode 101 and grid 104 of each digit by a dynamic grid drive by time-sharing, and thus predetermined characters or the like are displayed.
Next, description is given of a printed circuit board on which the integrated circuit device 300 is mounted. FIG. 6 is a schematic diagram showing the relationship between the printed circuit board and the integrated circuit device 300 in a conventional fluorescent display module.
The integrated circuit device 300 is disposed on the underside of the printed circuit board 320. On the periphery of integrated circuit device 300, the output terminals 311 (ao1-ao40) corresponding to the anodes 101 (A1-A40) of fluorescent character display tube 100 are disposed in the counterclockwise order. The output terminals 312 (go1-go15) corresponding to the grids 104 for fifteen digits are disposed in the clockwise order on the periphery of integrated circuit device 300. These positions are determined at the designing stage. Besides, other input terminals and power supply terminals (not shown) are also disposed on other regions of the periphery of integrated circuit device 300. Within the integrated circuit device 300, the above-mentioned circuits are electrically connected to the terminals.
The printed circuit board 320 includes forty input terminals 321 to which the output terminals 311 of integrated circuit device 300 are connected, and fifteen input terminals 322 to which the output terminals 312 of integrated circuit device 300 are connected. The printed circuit board 320 further includes forty output terminals 323 to which the input terminals 103 of fluorescent character display tube 100 are connected, and fifteen output terminals 324 to which the input terminals 106 of fluorescent character display tube 100 are connected. The printed circuit board 320 includes forty wirings 325 which connect each input terminal 321 to each output terminal 323, and fifteen wirings 326 that connects each input terminal 322 with each output terminal 324.
The forty wirings 325, which are connected to the output terminals ao1-ao40 of integrated circuit device 300 via the input terminals 321, are connected to the output terminal 323 corresponding to the input terminals AI1-AI40 of fluorescent character display tube 100, respectively. Likewise, the fifteen wirings 326, which are connected to the output terminals go1-go15 of integrated circuit device 300 via the input terminals 322, are connected to the output terminals 324 corresponding to the input terminals GI1-GI15 of the fluorescent character display tube 100, respectively. In FIG. 6, the solid lines representative of wiring 325 and 326 indicate that the wiring is disposed on the surface side of printed circuit board 320, and the broken lines representative of wiring 325 and 326 indicate that the wiring is disposed on the underside of printed circuit board 320.
In general, the positions where the input terminals of fluorescent character display tube are disposed, are designed by makers of fluorescent character display tubes allowing for the shape and size. On the other hand, the positions where the output terminals of integrated circuit device are disposed, are designed by makers of integrated circuit device. This creates a problem as follows. When a fluorescent character display tube and an integrated circuit device are mounted on a printed circuit board by a maker of fluorescent display module, the interconnection between the input terminals of printed circuit board corresponding to the positions of output terminals determined at the designing stage by the maker of integrated circuit device, and the output terminals of printed circuit board corresponding to the positions of input terminals determined at the designing stage by the maker of fluorescent character display tube, must be executed by multiple wiring.
For this reason, except when a maker of fluorescent display module designates the positions of output terminals of integrated circuit device to a maker of integrated circuit device maker so that the wiring to the positions of input terminals can be handled in a simple manner, the wirings on the printed circuit board must be routed so as to meet the positioning of output terminals determined by the maker of integrated circuit device, as long as an integrated circuit device for general purpose use is used.
For example, when the input terminals 321 and 322 as well as output terminals 323 and 324 are disposed on the printed circuit board 320 as shown in FIG. 6, the input terminals 322 and the output terminals 324 are, as to grids, positioned opposed in a one-to-one correspondence; this enables the wiring 326 to be simpler and shorter. As to anodes, however, the input terminals 321 and the output terminals 323 are not always positioned opposed in a one-to-one correspondence, and hence a complicated routing of the wiring 325 is required. Specifically, in order to prevent the wiring from intersecting each other, part of the wiring is located on both the surface side and underside of the printed circuit board 320. Most of the wiring is routed on the underside of integrated circuit device 300, but some of the wiring is routed on the periphery of integrated circuit device 300. This results in the increase in wiring region on the printed circuit board 320.
Accordingly, it is an object of the present invention to provide an integrated circuit device that allows a user to arbitrarily select the position of the input terminal of printed circuit board to be connected to each output terminal for an anode, and that allows the wiring on the printed circuit board to be simpler and reduced in wiring region.
According to one aspect of the present invention, an integrated circuit device comprises a first memory unit, a conversion part which converts parallel data read from the first memory unit into serial data, and a second memory unit. The second memory unit can write and read data indicating an order of reading the parallel data from the first memory unit and an order of converting the parallel data into the serial data.
In the present invention, the second memory unit is disposed between the counting part and the first memory unit and the reading order and the serial direction thereof are designated. Therefore, the correspondence between the address of dots and output terminals can be arbitrarily set up, when outputting display data that drive dots of minimum light emission unit in matrix configuration on the flat display board, from the display data output terminals of integrated circuit board. Consequently, when assembling a fluorescent display module, the display data input terminals of the flat display board and the display data output terminals of integrated circuit device can be positioned opposed in a one-to-one correspondence. Furthermore, the electrical interconnection between the display data input terminals of flat display board and the display data output terminals of integrated circuit device can be executed in a simpler wiring. Moreover, the decreased wiring area can reduce the manufacturing cost of printed circuit board.